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By M. Okido, W. Wei, L. Chai

The kinetics on the growth of Thiobacillus ferrooxidans was studied by use of series piezoelectric quartz crystal ( SPQC ). Arsenic ioninhibits the growth of Thiobacillus ferrooxidans, which is consistent with the previous results by other measuring method. This further demonstrates that the SPQC can monitor the chemical activity of the growth of Thiobacillus ferrooxidans. Cupric ion accelerates the growth of Thiobacillus ferrooxidans. The mechanism was discussed, it was considered that copper promotes the protein enzyme of Thiobacillus ferrooxidans, rustic yanin, to form over the range of cupric ion concentration studied. There action order of cupric ion in accelerating the bacterial growth is 0.067. The growth of Thiobacillus ferrooxidans is dependent on temperature, the apparent reaction activation energy decreases from25.56 kJ / mol to 18.32 kJ / mol because of the addition of 10 mg / L Cu(II) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%.

Jan 1, 2000

By David Burgess

The paper describes experiments at the Somerset Mine, Colorado, under a cooperative agreement between U.S. Steel and the U.S. Bureau of Mines. A test was made of the tube bundle method of mine air sampling which was developed for European longwall mines; some 300,000 running feet of tubing provided continuous monitoring at 39 locations. Carbon monoxide concentrations were obtained with standard deviations of less than 1 ppm and oxygen concentrations with standard deviations of less than 0.20 percent. A base level of CO index (ppm CO evolved/pct 02 removed)) was determined to be 0-20 through most of the passageways of the mine. However, in one working section where the coal was initially hot (about 180°F within a pillar) the CO index was demonstrably higher, >20 trending upward to about 60 when smoke appeared and the section was sealed. The data are discussed in terms of laboratory experiments on CO evolution from coals.

Jan 1, 1975

By Foluke Salgado de Assis

Este trabalho visa apresentar os resultados obtidos através de ensaios balísticos realizados em sistemas de blindagem multicamada. Seguindo as especificações da norma americana NIJ 0101.06, foram realizados ensaios utilizando munição de calibre 7,62x 51 mm, que possui velocidade acima de 800 m/s. A blindagem multicamada utilizada possui como camada frontal uma pastilha hexagonal cerâmica (alumina dopada com 4% de nióbia), segunda camada de compósito de matriz poliéster reforçada com tecido de juta e como terceira camada uma placa de alumino 5052 H34. A utilização de compósitos poliméricos reforçados com fibras naturais em substituição às fibras de aramida é de grande interesse, pois além de desempenharem a mesma função no sistema de blindagem, possuem um valor de mercado bem menor. Os resultados de profundidade de indentação na plastilina foram satisfatórios visto que atenderam a norma NIJ 0101.06 e utilizando a técnica de microscopia eletrônica de varredura, verificou-se que o compósito poliéster-juta capturou os fragmentos através do mecanismo de incrustação mecânica.

Aug 17, 2017

By Swaminathan Srinivasan, Jess A. Schroeder

"Landslide activity along U.S. 50 in Cincinnati, Ohio (USA) has caused roadway damage for decades. After a necessary closure of three lanes due to slope movements, emergency stabilization measures were undertaken to protect the roadway by providing a short-term solution necessitated by The Ohio Department of Transportation budget constraints. The landslide shear plane occurred on a sloping bedrock surface as much as 50 feet below grade. Drilled shafts were installed 40 feet downslope of the roadway shoulder and were heavily reinforced across the shear plane but steel reinforcing did not extend the full length of the shafts and was stopped well short of the ground surface. Instrumentation data has been collected for 11 years after construction has shown these “Stub Piers” have provided much more than a short-term solution and have provided an attractive alternate to conventional deep shafts or tieback drilled shaft options.INTRODUCTIONLandslide activity has occurred along U.S. Route 50 in western Cincinnati, Ohio for many decades. The site is located between North Bend and Addyston, Ohio on the right descending (cutting) bank of the Ohio River. Road distress caused by slope movements required periodic repairs over recent decades. Railroad tracks downslope of the roadway also showed signs of horizontal displacement and periodic repair. Visual evidence in 2005 suggested the shear plane extended below the US 50 roadway and extended out into the Ohio River.A weed and brush-covered slope extended down slope from the roadway at about 3H:1V for a vertical distance of about 20 feet. Above US 50, the hillside continued to rise more than 100 feet. There is a railroad right-of-way at the toe of the slope with the Ohio River bank just downslope of the railroad.In 2005, Terracon Consultants was retained by the Ohio Department of Transportation (ODOT) to perform a geotechnical study that included 17 test borings and inclinometer monitoring at 4 locations. Roadway damage was occurring (see Figure 1). After only a few weeks of monitoring, the inclinometer casings sheared off about 50 feet below grade, near the soil / bedrock interface (see Figure 2). Soon after, the roadway distress worsened, causing ODOT to close 3 of the 4 lanes to traffic and reroute traffic onto the remaining single lane and shoulder. Terracon was asked to develop a stabilization design under emergency repair conditions. However, both limited budget and time-related constraints necessitated a direction by ODOT that the solution be at least “pseudo” short-term (3 to 5 years)."

Jan 1, 2017

1. Domestic Production and Use: In 1980, 13 companies operated 33 primary aluminum reduction plants, with 3 firms accounting for 62% of production. Washington, Oregon, and Montana accounted for 30% of the total production; Texas, Louisiana, and Arkansas 19%; Tennessee, Alabama, and North Carolina 15%; other central and eastern States 36%. Based on published producer prices output of primary metal in 1980 was valued at over $7 billion. Aluminum consumption by 25,000 firms was centered in the East Central United States. Packaging accounted for an estimated 26% of domestic consumption in 1980, building 22%, transportation 21%, electrical 12%, consumer durables 7%, and other uses 12%.

Jan 1, 1981

By Barbara Mazzini Loureiro

As placas de circuito impresso (PCI) são materiais heterogêneos e sua composição pode variar em função do ano de fabricação, tecnologia empregada, propósito de utilização, legislações vigentes e país de origem, entre outros. Essas características interferem diretamente no valor econômico agregado a estes resíduos, pois dependem da composição dos mesmos, de tal maneira que as empresas recicladoras tomam como base essas informações no momento da aquisição da sucata. Assim, a classificação e caracterização de PCIs é de suma importância para o mercado de reciclagem de resíduos eletroeletrônicos. A fim de alcançar este objetivo foi realizada cominuição em moinho de facas utilizando grelhas com abertura de 9, 6 e 3mm. A etapa de caracterização incluiu ensaios de digestão em água régia, perda ao fogo, análises química quantitativa por ICP-OES e MEV/EDS. Verificou-se que o lote de PCI estudado possui 39,5% de material cerâmico, 34,5% polimérico e 26 % metálico. A porcentagem em massa de cobre na placa é de 14,28%, de ferro 3,73%, de ouro 0,012% e de estanho 1,29%. O lote não é lead free e é multilayer com quatro camadas de cobre.

Aug 8, 2018

By Francis J. Fratttali, Verda McLendon, Stanley J. Green

"INTRODUCTION During the first phases of the war emergency the shortage of aluminum prompoted the Bureau of Mines to investigate methods for using low-grade bauxites of high silica content and also clays as raw-material sources of this strategic metal. The Bayer process treats low-silica bauxites to provide the industry with a major portion of the purified alumina, which contains very low percentages of silica and other impurities. One of the methods investigated in the laboratories of the Bureau of Mines for low-grade materials is the lime-soda sinter process, which was studied on a pilot-plant scale. In this process, the alumina content of the alumina-bearing minerals Bs made water-soluble by sintering the raw material with limestone and soda. Simultaneously, the siliceous material is rendered insoluble. The sinter is extracted with an alkaline liquor, and the resulting extract liquor is treated as follows to recover the alumina: (1) Autoclaving with lime to remove silica as a zeolitic complex and (2) treatment with CO2 to precipitate alumina as the trihydrate (A1203.3H20). Figure 1 is schematic flow sheet of this process.As the process is cyclic, it is necessary that nearly all of the soda and alumina remaining in the plant liquors after carbonation be recovered. Upon passing through one cycle, these liquors contain 14 to 15 percent NaCO3 2 to 5 percent NaOH, 1 to 3 percent A1203, minor amounts of silica, and, with certain materials such as Pennsylvania diasporic clays, 0.5 to 1.0 percent Na2S04. Approximately 50 percent of the Na20 in these liquors must be returned, as soda ash, to the dry-grinding and raw-materials blending operations. Previous work (6)5/ on sulfate-free solutions demonstrated that two methods for recovering Na20 were feasible, namely: (1) Salting out Na2C03.H20 by evaporation of the carbonated solutions and (2) crystallizing Na2C03.10H20 by cooling the concentrated carbonated solutions."

Sep 1, 1947

By L. Su, S. Liu, K. Jiang, K. Xie

The reduction of iron dissolution and acid consumption is fairly important in the extraction of Ni and Co from laterite ores from both economic and efficiency perspectives. BGRIMM conducted detailed research to investigate the behavior of iron in a nickel laterite leaching process. The mineralogy of Ni and Co was studied. In limonite ore about 76% of nickel is present in goethite while in saprolite ore 79% of nickel is associated with magnesium and silicon minerals. Test work revealed that limonite can be decomposed completely with enough acid concentration during atmospheric leaching. More than 98% of Ni and Co were leached into solution while 85% of the iron was also dissolved with 130-140 g/L iron in solution. Iron precipitates as hematite in the temperature range 250-270?C without neutralization reagents. That’s why limonite is treated by high pressure acid leaching (HPAL) technology to achieve nickel extraction and iron precipitation in the same autoclave. BGRIMM’s test results indicated that the remaining acid in atmospheric leaching solution and acid released by iron precipitation at a lower temperature was enough to leach saprolite efficiently. The so-called inverse leaching technology leaches limonite at atmospheric condition and the leaching slurry combined with saprolite is pumped into an autoclave to leach saprolite at 150-170?C. In the autoclave iron precipitates as hematite without acid consumption. Total nickel and cobalt extractions in the test program were more than 90% with iron content in solution below 8 g/L. In this inverse process iron dissolves in the atmospheric leaching stage and precipitates as hematite in the low temperature leaching stage. Compared with HPAL the leaching temperature is reduced to 150-170 ºC from 250-270 ºC. Compared to atmospheric tank leaching acid consumption is reduced from 850-950 kg/t ore (atmospheric) to 550-650 kg/t ore (inverse).

Jan 1, 2016

By N. L. Wimmler

The chromite deposits along the Stillwater complex in Stillwater and Sweetgrass Counties, Mont., have at various times been studied and reported on by the Federal Geological Survey, the Montana Bureau of Mines and Geology, other Government agencies, and private interests, Several of the deposits were explored to a mall extent by the owners during the World War of 1914-17, but no production resulted. The importance of these deposits and the urgent necessity of developing large domestic sources of chromite were realized shortly before the beginning of the recent World War. These deposits were therefore investigated and developed by Government agencies and., as a result, now afford the largest known reserves of chromium in the United States. In 1939, under the authority of the Strategic Minerals Act, the Bureau of Mines and the Geological Survey made preliminary investigations of these deposits. As a result, the Bureau of Mines conducted an extensive program of trenching, diamond core drilling, and sampling. This work was begun in August 1939 and continued to April 1943. The Bureau of Mines also performed numerous metallurgical tests on the beneficiation of the chromite ores and concentrates and for the production of chromium metal there from. Research continues as a means toward utilizing these ores.

Jan 1, 1948

By W. W. Adams

Coal mining in the United States established a good safety record in 1939. The death and injury rates per man-hour of exposure to risk were favorable compared with most previous years, and the number of persons killed or injured in proportion to the quantity of coal mined was also lower than in any other year for which figures are available. Moreover, productivity per man-hour was higher than ever before. The number of man-hours of work performed increased 9 percent over 1938, but there was a slight decrease in the number of men employed. Reports from operating companies showed 539,375 men employed during the year, and the period of operation averaged 179 workdays per man. Man-hours of work numbered more than 678 million. Accidents to the workers resulted in 1,078 fatalities and 54,015 nonfatal disabling injuries, causing disability of the employee for more than the remainder of the clay on which the accident occurred. For each million man-hours of exposure of the employees to mining hazards the fatality rate was 1.59 compared with 1.78 for 1938, and the injury rate was 79.65 compared with 82.61 for 1938. Production of coal averaged 0.661 ton per man-hour compared with 0.637 ton in 1938. The weighted average length of the workday was 7.03 hours or virtually the same as the previous year's average of 7.04 hours. Measured in man-hours, the average period of employment per man was 1,257 hours in 1939 and 1,147 hours in 1938.

Jan 1, 1942

By Víctor R. Cabrera

Para un mayor avance en su producción, las minas de cielo abierto u "open it" de Marcona, utilizan unidades de mayor tamaño en el transporte, puesto que reduce el costo unitario del trabajo. En este aspecto, el objetivo del trabajo describe el uso de máquinas comprendidas para su uso, rendimiento de costo, pala, control de tiempo, tiempo de operaciones y el trabajo con traillas dentro de esta modalidad. etc. Como primer punto, las máquinas cargadoras, las palas mecánicas, etc, incrementan su tamaño constantemente y como tal, las operaciones de transporte cambiaron de uso de ferrocarril a de los camiones con 10,15, 20. 30 y 50 tonelajes por viaje. Posteriormente con el advenimiento de motores diesel, diseño, construcción, perforación y transporte de las máquinas cargadoras, se creó una minería de cielo abierto más económica, flexible y eficiente. En este punto, las operaciones estacionarias, sea con palas o las perforadoras de voladura, utilizaron preferiblemente la energía eléctrica que simplifica la operación y facilita el mantenimiento y las reparaciones. Mientras que las operaciones de perforación, voladura, carguío y acarreo se analiza las características de toneladas rotas por perforación, los cálculos de sobreperforación, los materiales explosivos usados, respectivamente. En cuanto la extracción de palas y volquetes, se evalúa la calidad del disparo, número de voloquetes, capacidad horaria. Finalmente en el trabajo con traillas, se evalúa la influencia del costo de las demoras relativas en las palas y los volquetes, pérdidas de la capacidad potencial de la pala cuando hay insuficiencia de volquetes, asi como las variaciones de la capacidad según la distancia de acarreo.

Jul 20, 1956

By Thomas M. Barczak

This US. Bureau of Mines report examines the roof and floor contact pressure provided by the interaction of a shield with the surrounding strata. Controlled forces were applied to an 800-ton two-leg shield in the Bureau's mine roof simulator; the distribution of forces acting on the canopy and base of the shield were measured with 24 hydraulic pressure cells. Several influential factors that affect the load distribution were investigated: (1) the magnitude of loading (leg pressure); (2) the profile of the canopy, principally the upward-sloping tip; (3) the base-lifting device; (4) horizontal load acting on the shield; and (5) compliancy of the immediate roof and floor. It was concluded that the shield does not develop full canopy or base contact without deformation of the strata. Maximum contact pressures are developed at the rear of the canopy and on the toes of the base. Less than 10 pct of the available shield capacity is developed at the canopy tip despite the design intention to ensure tip contact. Horizontal loading reduced the toe pressure acting on the base by as much as 75 pct. The base-lifting device exaggerated the inherently high toe loading, increasing the contact pressure by more than 200 pct.

Jan 1, 2010

By Albert L. Toenges

[sing tho ppsf; few Yomn t!le:.c. hcs beer. p. trqnd away frorn locomotive haulwe of cop2 frorn tile losdiw point to tho prop,nration plant of bitu~i- nnus-cod strip mlncc to a;~to~lzcd. h,71Jlr.:~. The qrostion has arisen rrhethcr this is alwqvs econ~nicd, rxcl the purpcrse or' tnf s investigation is to de- termine, if possible, the econonic limlt for ~~torieod had.we. sing tho ppsf; few Yomn t!le:.c. hcs beer. p. trqnd away frorn locomotive haulwe of cop2 frorn tile losdiw point to tho prop,nration plant of bitu~i- nnus-cod strip mlncc to a;~to~lzcd. h,71Jlr.:~. The qrostion has arisen rrhethcr this is alwqvs econ~nicd, rxcl the purpcrse or' tnf s investigation is to de- termine, if possible, the econonic limlt for ~~torieod had.we.]

Jan 1, 1938

By Albert L. Toenges

[During the past few years there has beer trend away from locomotive haulage of coal from the loading point to the preparation plant of bituminous-coal strip, miner to motorized. haulage. The question has arisen whether this is always economical, and the purposes of this investigation is to determine, if possible the economic limit for motorized haulage. The operators of strip coal mines and of open-pit ore mines have shown great interest in this problem, and it is thought that the findings of this investigation will. Provo helpful to them.]

Jan 1, 1938

By J. W. Langford

A more effective method of fracturing and chipping the formation is necessary to significantly increase the productivity of blasthole drilling with a roller cone bit. The conventional rotary blasthole bit engages the formation and initiates spalls, chipping and fractures in the formation at a rate dependent on the amount of pull down force applied by the drill. The rotary speed of the drill increases the number of fractures and creates drilled chips that are removed from the hole by the air circulation. An engineering project was motivated to develop a low pressure, low impact downhole percussion hammer to provide an overstrike force to a blasthole bit, in addition to the conventional pull down force and rotary speed. The objective of the project was to utilize existing rig air packages in the range of 50-110 psig and provide an overstrike force to the bit in the range of 1100-1500 impacts per minute. Laboratory testing performed on Barre granite achieved, on average, a 40% improvement in rate of penetration. This performance has been confirmed in actual blasthole drilling in copper and iron ores mines. During the testing phase, additional unexpected benefits have also been realized.

Jan 1, 2011

By H. J. Gerritsen

From presently available components a portable, rugged, reliable apparatus can be built which will be able to detect methane concentrations of 0.1% and lower in air. Sensitivity and design considerations of the apparatus are given. Ways to build even simpler and cheaper apparatus in the future are indicated. Traditionally the problem of detecting and monitoring the presence of dangerous gases present in small concentrations in air has been a difficult one. Whether canaries,' or sophisticated chemical or thermal conductivity methods are used, they seem to be either slow, cumbersome, or otherwise not completely satis factory. A seemingly natural way of gas detection is to measure the strength of absorption undergone by light of a wavelength that the gas to be detected absorbs. This method has been difficult to apply in view of the low power output over a narrow wavelength range in the infrared from traditional glow bar light sources. Besides, the apparatus to select such a narrow band of wavelengths is quite costly and complex. The use of a laser solves these problems simultaneously. Although a variety of lasers are available to detect a variety of gases (such as carbon monoxide or methane) whose early detection would be desirable, this paper deals exclusively with the use of lasers for methane detection. ABSORPTION SPECTRUM OF METHANE IN AIR The absorption spectrum of pure methane is very well known.2-4 There are four fundamental vibrations, all occurring in the infrared of which only two absorb strongly. They occur at 3.3 µ and 7.7 µ. The absorption spectrum is quite complicated due to the fact that the methane molecule can rotate in a variety of rotational quantum states. These rotational states are furthermore split by anharmonic forces such as the Coriolis force.4 When methane is present in air at atmospheric pressure, much of the very fine structure due to the anharmonic force is washed out since the pressure broadening is of the same magnitude as the splitting due to anharmonicity. For most of the spectrum at 3.3 µ, the rotational lines are typically separated by 0.01µ while the individual linewidth is 0.0001 µ. It is thus very important that the laser emit at a wavelength that coincides with one of these rotational lines. Before elaborating on the point that such a laser exists and how it performs, it is necessary for later discussion to point out that in the

Jan 1, 1967

By K. C. Dean

During the course of the investigation of manganese mineral occurrences in the western United States, the Bureau of Mines collected several lots of ore' from properties in the vicinity of Winkelman, Ariz. As none of the ores would be marketable directly, an investigation was made to determine their amenability to concentration by ore dressing. The Geronimo group of claims is in Pinal County, 8 miles west of Winkelman, Ariz. The manganese oxides occur as cementing material in ore zones of conglomerate. Representative samples of a 2-ton lot of ore cut from outcrops of two lenticular deposits were laboratory-tested. Two 1-ton samples from the Benningfield property were similar in physical characteristics but differed in grade. This claim is 11-1/2 miles south of Winkelman and about 1 mile west of the San Pedro River on the south side of Putman, Wash. The manganese minerals occurred as nodules and lenses, replacing limestone, in a capping over a dark, igneous dike. The North Star group consists of five claims on the west side of the San Pedro River 14 miles south of Winkelman. The ore consists of a low-grade, manganese oxide-calcite occurrence interspersed with stringers of higher-grade material and is present as filling in a fissure zone in porphyry. Two samples were obtained by the examining engineer; one sample represented run-of-mine material, the other represented ore from the vein that could be hand-sorted or selectively mined.

Jan 1, 1952

By G. R. Hopkins

According to reports received by the Bureau of Mines, Department of the Interior, as of January 1, 1934, there were 591 completed refineries in the United States, an increase of 86 ever the total reported at the beginning of 1933 and the largest total ever recorded. It should be noted that the 1934 total, although large, probably does not include more than half of the "pot-still" plants of 1 barrel to 50 barrels daily capacity which have sprung up within the last 2 or 3 years and about which very little information is available. However, the combined operations of these snail refineries are of negligible importance as altogether they refine less crude than one plant of average size. Of the completed plants, 454 were operating on January 1, 1934 and 137 were shut down. In addition, 13 refineries were under construction on January 1, 1934. Compared with the previous year these data indicate a marked increase in the number of operating plants, little change in the number of inoperative plants, but a decline in' the number being built. The material gain in the number of operating plants resulted primarily from the construction off approximately 25 refineries, averaging about 100 barrels capacity in the Kooky Mountain district, as well as from the addition of about 20 plants in the East Texas field.

Jan 1, 1934

By J. Duncan Keppie

"Auriferous quartz veins occupy zones of dilation. Foldgenerated dilation zones are systematically distributed and are dependent upon the folding mechanism. Comparison of natural and theoretical folds indicates that different mechanisms operated in the Halifax and Goldenville formations.In the slates of the Halifax Formation, the folds are of similar type and internal strain is most intense in the limbs. This internal strain is probably accommodated with little or no dilation.In the meta-sandstone and slates of the Goldenville Formation, a combined flexural and tangential longitudinal strain mechanism, modified by pure strain, produced the folds. Tension fissures produced by this mechanism are: (a) saddle 1'eef veins in slate horizons, (b) veins normal to bedding in meta-sandstone layers in the fold hinges,(c) veins along faults in the cores of tight fold hinges and (d) zones of en- échelon veins in slate honzons in the limbs of folds. Because veins in fold hinges (a, b and c above) account for most of the gold production in the Meguma Group, other factors controlling the distribution and size of these veins are summarized below.1. The size of saddle reef veins is controlled by the curvature of the fold hinge. Thus, a Curvature Index greater than 600 degrees indicates a promising prospect, where"

Jan 1, 1976

By Charles Will Wright

This paper is one of a series dealing with mining problems and summarizing the data contained in the Information Circulars on individual mines that have been prepared by the managers or superintendents and published by the Bureau of Mines. The purpose of this paper is to present the problems encountered in the development of an efficient mine organization and to show the means used by certain mining companies in promoting efficiency. There is also a discussion of the advantages and disadvantages of the various systems of paying and handling labor and a description of their application at the individual mines.

Jan 1, 1932